Biomedical Engineering Reference
In-Depth Information
Glass
Ti6Al4V
LA-purified
LA-not purified
AD
HiPco
(A)
(B)
(C)
FIGURE 18.4
Fluorescent staining of osteoblasts adherent to glass, titanium alloy, and differently prepared SWCNTs (SWCNT
films prepared by laser ablation (LA) (purified and not purified), by arc discharge (AD), and by HiPco
processes) after 48 h. (A) Visualization of vinculin (red) and nucleus (blue), (B) visualization of actin (green)
and nucleus (blue), (C) visualization of vinculin (red), actin (green), and nucleus (blue). (For interpretation of
the references to color in this figure legend, the reader is referred to the web version of this topic.)
Reproduced with permission from Ref.
[28]
.
defects (1.5
1.5 mm) in the left femur regenerated more effectively by implanting MWCNT-
coated sponges in comparison with pure collagen sponges. At 28 and 56 days after implantation,
new bone attachment to MWCNTs was observed (
Figure 18.5
).
As for using CNFs in scaffolds for tissue regeneration, many literatures have referred to Elias
et al.'s
[32]
study as the first report. In 2002, Elias et al. studied the in vitro culture of osteoblasts on
CNF compacts with different fiber dimensions (i.e., 100 nm or less or conventional CNFs with dimen-
sions larger than 100 nm). They analyzed functions of osteoblasts, like proliferation, synthesis of intra-
cellular proteins, ALP activity, and deposition of calcium-containing mineral, to evaluate the effect of
CNFs dimension on cell behaviors. After 3
3
21 days of culture, it was interesting to find that prolifera-
tion and differentiation of osteoblasts were enhanced on CNFs with smaller diameters. This study pro-
vided the first evidence of the size of the CNFs playing an important role in increasing osteoblast
functions because those CNFs used in their study were not functionalized with bioactive molecules
and were in their raw state. In another study, Price et al.
[33]
tested the effect of some select properties
of carbon fibers (specifically, dimension, surface energy, and chemistry) on osteoblasts and osteoblast
competitive cell line (e.g., fibroblasts, chondrocytes, and smooth muscle cells) adhesion. In the study,
researchers dispersed CNFs in polycarbonate urethane (PCU) to create PCU/CNF composites. They
found that the composites with smaller scale (i.e., nanometer dimension) carbon fibers promoted osteo-
blast adhesion but decreased the adhesion of other cells. Surface energy of CNFs was considered as
another material property to have influenced the initial adhesion of competitive cells and that these
cells' adhesion decreased when CNF surface energy was increased. Similarly, CNT-incorporated poly-
mer composites also showed such cell selectivity. Mei et al.
[34]
electrospun MWCNTs into PLLA
